Epexochus Reitter

Meregalli, Massimo & Talamelli, Fabio, 2009, Revision of the genus Epexochus Reitter, with description of three new species (Coleoptera: Curculionidae: Lixinae: Cleonini), Zootaxa 2011, pp. 47-68 : 48-50

Epexochus Reitter

Epexochus Reitter, 1913: 40 ; Alonso-Zarazaga & Lyal, 1999: 191. Cleonus (Epexochus) : Csiki, 1934: 39.

Type species: Cleonus lehmanni Ménétries, 1849 , by monotypy.

Redescription. Habitus. Size large, body elliptical. Integument smooth, lacking granules or tubercles, hind wings vestigial.

Vestiture. Integument densely covered with whitish and brown, aciculate to lanceolate, acuminate, glossy scales forming various patterns on pronotum and elytra; scales simple or with short basal lateral projections, with large median and minute lateral teeth; underside of rostrum with usually simple, whitish or yellowish, aciculate scales; underside of head with minutely digitate, white, oval scales; underside of thorax with white elliptical scales, usually finely digitate, bifid or trifid, in part simple, aciculate; ventrites with long, aciculate scales, usually simple or with short basal projections, whitish on the whole surface and brown in a basal stripe, sometimes reduced to two broad patches; hair-like setae present, whitish, hyaline or yellowish, relatively dense, inserted in larger punctures of integument, seldom very short and barely distinct, usually relatively long, suberect on sides of pronotum and sides and declivity of elytra; on dorsum of elytra setae disposed in several series on whole surface; on legs setae often very dense, nearly half as long as tibial width; on ventrites setae usually dense, obliquely inserted, long.

Rostrum robust, straight, dorso-lateral margins not keeled, rounded or very slightly raised; median line distinct, not sharply elevated nor acutely keeled, with a triangular plate broadened anteriorly at its side; dorsum laterally of median line and triangular plate moderately impressed, forming two longitudinal, usually curved, shallow grooves; epistoma subtriangular, moderately prominent, apex straight; rostrum in lateral view straight, thick, about three times as long as high; dorsum moderately curved downwards behind antennal insertion, underside straight basally and curved downwards before mouthparts, keels on postmentum linearly converging basally; scrobes narrow, subsinuate, glossy, posterior part, seen from below, broadened, rounded; upper margin directed towards, and interrupted before, lower margin of eye; lower margin reaching underside near base of rostrum.

Mouthparts. Maxilla (Figs. 19–20) with curved cardo, stipes as long as wide, more strongly sclerotised externally, with one long and several short setae; palpifer subquadrate, densely setose on outer side and on apex; mala semicircular, with six lateral teeth, the four lower ones extremely strong, the two upper ones thinner; three secondary teeth on lower face; basal setae long, curved upwards; maxillary palps threesegmented, segment 1 broader than long, widened laterally, setose; segment 2 conical, moderately transverse, with one apical seta; segment 3 shortly conical, lacking setae. Labium subquadrate, with three primary and a few smaller lateral setae; ligula distinct, rounded at apex; in lateral view labium thickened, with a distinct median projection; labial palps undifferentiated.

Antenna slender. Scape subsinuate, thin, moderately thickened at apex. Funicle 7-segmented, segment 1 short, globose, segment 2 slightly longer than 1; segments 3–6 globose, segment 7 larger, partly fused to club. Club long elliptical, segment 3 as long as 1 and 2 together.

Head broad, transverse, vertex evenly convex, eyes large, flat, ovate-elliptical, nearly symmetrical, lower margin narrowly rounded.

Pronotum as long as wide or weakly transverse, faintly convex, sometimes sub-campanulate; base truncate or weakly curved or lobed towards scutellum, sides sublinear or weakly broadened towards middle of length, maximum width at base or in basal half; apex straight, indistinctly prominent above head; postocular lobes rounded, moderately or barely developed, with a fringe of dense, orange postocular setae; surface uniformly and minutely punctulate, with few slightly larger, isolated punctures, granules absent on dorsum and sides, median line not or barely differentiated.

Scutellum visible but small, triangular.

Elytra ovate-elliptical, humeri not expanded laterally, sides moderately broadened, evenly converging at apex; in lateral view dorsum barely convex, declivity oblique, even, not sharp. Striae 10 in number, narrow, shallow, with barely delimited or nearly indistinct punctures; at apex stria 1 joined to stria 10, stria 2 to 9 and stria 3 to 8; on declivity stria 4 joined to 5 and stria 6 to 7. Intervals broader than striae, odd intervals as wide as or barely wider than even ones, usually very slightly convex, higher near base, or completely flat; base of intervals 7–9 fused, striae 7 and 8 not reaching base. Surface minutely punctulate, lacking any granules.

Legs slender. Trochanters triangular, barely longer than wide. Femora thin, hardly thickened in middle. Tibiae a little longer than femora; fore tibia with outer margin rectilinear or slightly curved outwards near apex; inner margin weakly sinuate; apex sinuate, barely expanded, with a fringe of apical setae; uncus strong; internal subapical tooth absent in both sexes; middle tibia slightly shorter and narrower; hind tibia longer, slightly to moderately curved behind, widened towards apex. Tarsi well developed, segments broad, triangular, sides with more or less well developed tuft of downward-directed setae; segment 3 moderately bilobed; underside densely setose but lacking a complete pad, which is limited to a small setose area on centre of segment 3, more distinct on fore tarsi; onychium long, often slightly broadened in middle; claws narrowed from base to apex, long, separate nearly from base, divaricated from basal third ( Fig. 26 ).

Venter. Prosternum at apex with a broad emargination, weakly protruded towards fore coxae; space in front of coxae half as long as diameter of coxae, strongly oblique, smooth; intercoxal process relatively well developed, protruding between coxae; these round, separated by prosternal process, subcompressed and emarginate on anterior side. Mesothorax with middle coxa round, mesepisternum broad, triangular, extending towards median part of mesothorax; mesepimeron slightly broadened dorsally, intercoxal process subquadrate, large. Metathorax narrow, as wide as diameter of mesocoxa; metepisternum broad, subrectangular; metacoxae transverse, widely separated. Ventrite I with broad, subtruncate intercoxal process, sinuate at apex, concave in ɗ and nearly flat in Ψ; ventrite II slightly narrower, 1.5x as long as III, flat or barely concave in central part on ɗ and convex on Ψ; ventrites III and IV of equal size, V slightly longer than IV, evenly curved at apex in Ψ and truncate in ɗ.

Genitalia. Aedeagus slender, tubular, curved; lamella short, subacute or rounded. Sternite VIII of Ψ Vshaped, arms connate at base, narrow, nearly linearly widened; lamina delimited laterally by the arms, sclerotised only near apex. Spermatheca small, with narrow and curved cornu, thickened nodulus and short lateral ramus. Hemisternites short, moderately broadened basally, styli apical, short; symbiont pouches relatively short, as long as hemisternites, annuli not sclerotised.

Remarks. Epexochus is closely related to Eurycleonus Bedel, 1907 from northern Africa and Sinai and to the sympatric, monotypic genus Leucochromus Motschulsky, 1860 , these three genera forming a monophyletic group (Meregalli & Silvestro in press). The last genus differs from Epexochus as follows: rostrum with a broad median ridge; pronotal disc with a median furrow and two broad, glossy, bare lateral ridges, a wide squamose, longitudinal stripe along ridges, another glossy ridge on dorso-lateral margin and some round, smooth, glossy patches on sides; even elytral intervals with raised glossy margins forming longitudinal black keels; basal tarsal segment as long as wide and barely longer than segment 2; claws narrow, widely divergent from base; sternite VIII of Ψ with plate sclerotised along entire length of arms; scales white, aciculate or elliptical, always simple. Eurycleonus is more similar to Epexochus and appears to be its sister taxon; apart from its distinctly larger size it differs in its scales being bifid on the whole body, with strongly elongate teeth, its tarsal segment 1 short, as long as wide, and the claws connate up to middle of their length, and in the sternite VIII of the Ψ having the plate sclerotised on both sides along the arms.

Figures

FIGURES 21 – 39. Epexochus, genitalia, claws and scales. Female genitalia (21 – 23: specimen from Kzyl-Dzhar; 24 – 25: specimen from Aulie-ata). 21, 24, sternum VIII; 22, 25, spermatheca; 23, hemisternites. Claws. 26, specimen from Borokhoro. Aedeagus, dorsal and lateral views and detail of apex. 27, 30, 35, specimen from Koibun; 28 – 29, 32, specimen from Elton lake; 31, specimen from Dzharkentsk; 33, specimen from Betpak; 34, specimen from Borokhoro. Elytral scales. 36, holotype of E. lehmanni; 37, holotype of E. korotyaevi; 38, holotype of E. voriseki; 39, paratype of E. mongolicus. Scale bars: 21, 23 – 24, 27 – 31: 1 mm; 26, 32 – 35: 500 μm; 36 – 39: 100 μm.